The primary objective of this investigation is to study the mechanisms of RNA biosynthesis in Escherichia coli and in bacteriophage-infected E. coli. The major emphasis will be on the structure, function and mechanism of action of the rho transcription termination protein. The enzymatic properties of the RNA-dependent ATPase activity of rho will be studied. This will include an analysis of the kinetics of the reaction, the effects of inhibitors and the minimum requirements for an RNA to activate the ATPase reaction in the termination of RNA synthesis catalyzed by RNA polymerase. The mechanism of rho action in termination will be investigated in detail using specific restriction endonuclease-generaged fragments of bacteriophage lambda DNA that code for the synthesis of a single RNA transcript that can be terminated by rho action. Further proof that rho is the product of a gene that maps between the ilv and cya loci on the E. coli genetic map will be obtained and an attempt will be made to isolate mutants with temperature-sensitive rho factor. These mutants will be used to study the effects of inactivation of rho factor on RNA metabolism in vivo. Studies on the properties of defective rho factors isolated from polarity suppressing (suA) strains of E. coli will be continued to determine how rho is involved in causing transcriptional polar effects.